WO2020030084A1

WO2020030084A1 - Process for smelting and separating rare earth concentrate using combination method

Info

Publication number: WO2020030084A1
Application number: PCT/CN2019/099932
Authority: WO
Inventors: 黄小卫; 冯宗玉; 孙旭; 徐旸; 王猛; 王良士; 夏超; 刘向生; 赵龙胜; 张永奇
Original assignee: 有研稀土新材料股份有限公司
Priority date: 2018-08-10
Filing date: 2019-08-09
Publication date: 2020-02-13
Also published as: AU2019316882B2; ZA202101505B; US20210310100A1; CN112534072A; AU2019316882A1

Abstract

Disclosed is a process for smelting and separating a rare earth concentrate using a combination method, comprising treating a rare earth concentrate containing bastnaesite by using a method of roasting under an atmosphere - leaching with hydrochloric acid - roasting with sulfuric acid, and controlling the manner of stepping acid leaching with a low concentration hydrochloric acid during the leaching with hydrochloric acid so as to obtain a rare earth solution with a high concentration (150-250 g/L REO), such that the leaching rate of Ce reaches 60% or more, and the content of F^- in a leaching liquor is reduced by aging, and further recovering rare earth from leaching residue by roasting with sulfuric acid - leaching with water, wherein the total yield of the rare earth reaches 95% or more. The whole process has a wider industrial applicability, can comprehensively treat a variety of complex rare earth minerals, and can realize environmentally friendly, efficient and clean production of mineral-type rare earth concentrates.

Description

Smelting separation process for processing rare earth concentrate by combined method

This application is based on a Chinese patent application with an application number of CN201810912079.3 and an application date of August 10, 2018, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is incorporated herein by reference.

Technical field

The invention belongs to the technical field of rare earth smelting and separation, and particularly relates to a smelting and separating process for treating rare earth concentrates by a combined method. One or more mixed rare earth minerals.

Background technique

China's rare earth resources are mainly based on mineral light rare earth mineral resources, accounting for more than 90% of the total reserves. Industrial rare earth minerals are mainly fluorocarbon cerium and monazite, whose light rare earth content is as high as 96% -98%. According to statistics, the light rare earth deposits with industrial application value are mainly Baotou Baiyun Ebo rare earth mine, Sichuan Panxi Mianning rare earth mine, and Shandong Weishan rare earth mine.

At present, about 90% of Baotou mixed rare-earth ore is smelted using the third-generation patented sulfuric acid method developed by the General Research Institute, that is, concentrated sulfuric acid for enhanced roasting decomposition, water immersion, neutralization and impurity removal, ammonium carbonate precipitation-hydrochloric acid dissolution Or P507 and P204 extraction transformation and separation, this process has the advantages of simple and controllable, easy continuous large-scale production, high rare-earth recovery rate, etc., and does not require high concentrate grades and low operating costs. However, in the sulfuric acid-enhanced roasting process, complex exhaust gas containing sulfur and fluorine is generated, which is difficult to recover and treat, and the equipment investment is large, thereby increasing the overall operating cost.

The fluorocarbon cerium ore generally adopts the oxidation roasting-hydrochloric acid leaching chemical treatment process. The concentrate is decomposed by oxidation roasting to generate hydrochloric acid-soluble rare earth oxide, rare earth fluoride or rare earth oxyfluoride, and cerium is oxidized to tetravalent Ions, and during the leaching process of hydrochloric acid, trivalent rare earths are leached to obtain cerium-less rare earth chloride, cerium and some trivalent rare earths, fluorine, and thorium are left in the soluble slag, and the alkali is used to remove the fluorine to obtain the cerium-rich The slag can be used to produce ferrosilicon alloys, or to produce cerium oxide with a purity of about 98% after reduction and leaching. The rare earth cerium chloride is separated into a single rare earth by the P507 extractant. The advantage of this process is that the investment is small and the production cost is low, but the disadvantage is that the process is discontinuous, and the cerium, praseodymium and fluorine do not dissolve in the slag during the hydrochloric acid leaching process. After the slag undergoes alkali conversion, the fluorine will The form of sodium fluoride enters the waste water, and thorium and fluorine are dispersed in the slag and the waste water, which is difficult to be recycled. As a result, the entire process not only pollutes the environment, but the recycling purity of the cerium product is only about 98%, which has a low use value.

In recent years, with the gradual improvement of domestic environmental protection regulations, the emission standards for pollutants in the rare earth industry have become increasingly strict in various places. The Ministry of Environmental Protection promulgated the world's first "Rare Earth Industrial Pollutant Emission Standards" (GB26451-2011) on January 24, 2011. It monitors and monitors water and air pollutant emission limits for existing and newly-built rare earth industrial production facilities. All made explicit requirements. On May 10, 2011, "Several Opinions of the State Council on Promoting the Sustainable and Healthy Development of the Rare Earth Industry (Guo Fa [2011] No. 12)". The New Environmental Protection Law, which came into effect on January 1, 2015, clearly stipulates the implementation of a total pollutant emission control system for key industries. In October 2016, the Ministry of Industry and Information Technology issued the "Rare Earth Industry Development Plan (2016-2020)", which made clear requirements for the production indicators and green development indicators of the rare earth industry during the "13th Five-Year Plan" period. The above-mentioned national policies have great strategic significance for the pollution control of rare earth production, and the rare earth industry also urgently needs green and environmentally friendly new smelting and separation technologies.

Summary of the invention

In order to solve the problem that the existing fluorocarbon cerium ore treatment process has a low Ce content in hydrochloric acid leaching solution, the cerium oxide product recovered from the cerium-rich slag has low purity, and the mixed concentrate processing process has a high concentration of fluorine and sulfur in flue gas emissions during sulfuric acid roasting, and a high treatment and recovery cost , Low concentration of rare earth leachate. The smelting separation process for treating rare earth concentrates by the combined method according to the present invention includes the following steps:

(1) roasting and decomposing the rare earth concentrate in a certain roasting atmosphere to obtain a roasted ore;

(2) adding the obtained roasting ore to leaching rare earth with hydrochloric acid, and separating the rare earth leaching solution and leaching slag by solid-liquid separation;

(3) After the obtained leaching slag is subjected to dehydration treatment, concentrated sulfuric acid is added for roasting, and the roasted product is collected and subjected to water leaching, neutralization, and impurity removal to obtain a rare-earth sulfate solution.

Preferably, the rare earth concentrate according to the present invention includes, but is not limited to, fluorocarbon cerite or a mixed type rare earth ore of monazite or xenotime or one type of monazite or xenotime.

In the step (1), the roasting atmosphere in the roasting step includes water vapor or a weakly oxidizing atmosphere; the weakly oxidizing atmosphere includes, but is not limited to, one or more of N ₂ , CO, CO ₂ , air, and an inert gas. This kind of atmosphere can reduce the oxygen content by controlling the gas flow rate; the purpose of the water vapor atmosphere is to defluorinate and obtain pure HF as the recovery product; the purpose of the weakly oxidizing atmosphere is to reduce the oxidation rate of cerium and improve the rare earth Leaching yield.

In the step (1), the HF gas obtained after defluorination is adsorbed and recovered by using a rare earth oxide or a rare earth hydrated oxide to obtain a fluorinated rare earth product. The principle is that the rare-earth oxide forms a polynuclear hydroxyl compound in water, causing ion exchange between OH ^- and fluoride ions on the rare earth oxide to achieve a double fluoride removal effect. Through adsorption recovery, the HF produced in the defluorination roasting and decomposition process of the rare earth concentrate can be effectively recovered to obtain a fluorinated rare earth product, and the tail gas can be discharged in accordance with standards, which has significant environmental protection benefits.

In the step (1), the roasting temperature of the roasting step is 350-650 ° C, preferably 400-600 ° C, where the roasting temperature is increased within a certain range, which can increase the rare earth leaching rate; the time of the roasting step is 0.5-6h, which can extend the roasting time within a certain range, which can increase the rare earth leaching rate.

In the process of the present invention, the roasting process of the rare earth concentrate is mainly a decomposition process of RECO ₃ F in the concentrate, and its reaction formula is: REFCO ₃ = REOF (CeOF) + CO ₂ ↑. In the presence of water vapor, a defluorination process occurs, and its reaction formula is: REOF + H ₂ O = RE ₂ O ₃ + HF ↑. The removed HF gas is recovered by an adsorbent such as a rare earth oxide. The reaction formula is: 6HF ↑ + RE ₂ O ₃ = 2REF3 + 3H ₂ O.

In the step (2), the concentration of the hydrochloric acid is 3-10 mol / L, preferably 4-7 mol / L, and the ratio of the amount of hydrochloric acid to the roasted concentrate is 0.4-2.0 mol hydrochloric acid / 100 g of rare earth concentrate, preferably It is 0.7-1.5mol hydrochloric acid / 100g rare earth concentrate.

In the step (2), the hydrochloric acid leaching step is preferably two or more steps of hydrochloric acid counter-current leaching. After the first step of hydrochloric acid leaching, solid-liquid separation is used to obtain one rare earth leaching solution and one leaching slag. Hydrochloric acid leaching. The rare earth leaching solution and the leaching slag of this step are obtained through solid-liquid separation. The rare earth leaching solution in this step is returned to be used as the bottom water for the hydrochloric acid leaching in the previous step. The leaching slag in this step can be subjected to the next step of hydrochloric acid leaching.

In the step (2), the method for adding hydrochloric acid is to carry out continuous co-current leaching of 2-5 stages in the leaching process, and control the hydrochloric acid to be added in a concentration gradient during each stage of leaching, and the first stage is diluted. Concentration of hydrochloric acid, higher levels of hydrochloric acid are added in the last few stages to maintain the acidity of the mixed solution at 0.01-0.6 mol / L, and preferably 0.05-0.3 mol / L. The lower the acidity, the more favorable the rare earth leaching. The purpose is to ensure that the tetravalent Ce is not reduced after entering the solution, and increase the leaching rate of rare earth and fluorine; through stepwise leaching, a higher rare earth concentration can be obtained, and the rare earth concentration in the leaching solution reaches 150-250 g / L. At the same time, because the residual acid content of the leachate is effectively reduced, the neutralizer consumption in subsequent processes is also reduced.

In the process of hydrochloric acid leaching of roasted ore, hydrochloric acid leaching is performed at a lower temperature because F is mainly present in the solution as a [CeF _x ] ^4-x complex, and low temperature conditions are favorable for [CeF _x ] ^4-x The steady state of the coordination compound can make more dissolution of rare earth and F, and the leaching rate of rare earth reaches 70% -95%.

The leaching temperature of the hydrochloric acid leaching step is controlled to be 10-75 ° C, preferably 20-65 ° C, and the total reaction time is controlled to be 0.5-10h, preferably 1-6h, mainly to improve the leaching rate of rare earth and F.

In the step (3), the dehydration step is a natural dehydration and / or drying method, and the moisture content of the dehydrated leaching slag after the treatment is preferably less than 10%, and the REO content of the dewatering leaching slag is 20%- 60%, mainly REPO ₄ , can be mixed with other rare earth concentrates for sulfuric acid roasting.

In the step (3), the mass ratio (w / w) of the concentrated sulfuric acid to the leached slag after dehydration is 0.3-1.2: 1, and preferably 0.5: 1. The scheme of the present invention is compared with the prior art. Technology, a large number of rare earths have been leached in the 1-2 step, and the sulfuric acid use amount is greatly reduced in the sulfuric acid roasting step.

In the step (3), the temperature of the sulfuric acid roasting step is 200-450 ° C, and preferably 200-220 ° C or 250-350 ° C, and the roasting time of the roasting step is 1-4h;

The temperature of the water leaching step is 20-50 ° C, and preferably 25-40 ° C, preferably the leaching time is 2-5h, and the leaching solution can be neutralized with a basic substance to a pH of 4-4.5, and the sulfuric acid obtained The concentration of the rare earth solution is 25-45 g / L (REO).

In the step (3), the hydrochloric acid leaching slag is first washed with water, and the washing water: leaching slag ratio (w / w) is 0.5-10: 1, preferably 0.5-5: 1. 0-50%, preferably 0-30%. The treated washing water contains a rare earth concentration of 5-50 g / L (REO) and a H ⁺ concentration of <0.1 mol / L. The purpose of the washing water is to wash the rare earth chloride entrained in the leaching slag into the solution, further increase the rare earth leaching rate, and remove the chloride ions that may cause corrosion to the subsequent sulfated roasting equipment. A certain degree of dehydration treatment can reduce the The sulfuric acid is used to strengthen the dilution of concentrated sulfuric acid in the roasting process, and the water washing liquid is used for the rare earth concentrate slurrying or the preparation of hydrochloric acid in step (2) to realize the closed-loop circulation of the water washing liquid.

The step (3) further includes a step of adding the obtained rare earth sulfate solution to iron powder for configuration, and the amount of the added iron powder is 2% -10% of the mass of the hydrochloric acid leaching slag.

The step (3) further includes a step of extracting and transforming the obtained rare earth sulfate solution to obtain a rare earth chloride solution, and extracting and separating to obtain a single rare earth compound.

The extraction transformation step is a transformation process by precipitation or extraction.

The step (2) further includes a step of subjecting the obtained rare earth leaching solution to aging treatment, solid-liquid separation to obtain a rare earth chloride solution and a fluorinated rare earth product; and combining the obtained rare earth chloride solution with the one described in step (3). A rare earth chloride solution obtained by transformation of the rare earth sulfate solution is combined, and a single rare earth compound is obtained by extraction and separation.

The aging step is performed under standing or stirring conditions, and filtering is performed to obtain lanthanum cerium fluoride product; the temperature of the aging step is controlled to 60-90 ° C, further preferably 65-80 ° C, and the control is preferably performed. The temperature of the aging step should be equal to or higher than the hydrochloric acid leaching temperature; the time of the aging step is 0.5-10h, preferably 1-4h.

Since F in the leaching solution mainly exists in the form of [CeF _x ] ^4-x complex, the electrode potential of Cl ₂ / Cl ^– decreases with increasing temperature, which is significantly lower than that of Ce ⁴⁺ / Ce ³⁺ electrodes. Potential, the formed [CeF _x ] ^4–x complex is reduced by Cl ⁻ and releases F ⁻ ; the generated F ^– immediately binds to RE ³⁺ (mainly Ce around F ions) to form a rare earth fluoride precipitate In addition, the solubility product of rare earth fluoride has an inverse relationship with temperature. The higher the temperature, the lower the solubility product, such as CeF ₃ , 25 ° C, Ksp = 8.0 × 10 ^-16 ; 100 ° C, Ksp = 9.3 × 10 ^-18 , further promote the precipitation of rare earth fluoride. In this way, the high-temperature aging step is used in the process of the present invention, which can effectively separate F from the leaching solution into the slag. The F content in the leaching solution is <8mg / L. Increasing the aging temperature and extending the aging time can further reduce the F content. To avoid the effect of F on subsequent extraction and separation.

In this step, the aging treatment can obtain a precipitate of rare earth fluoride, and it is preferable to control F <8 mg / L in the leaching solution, and more preferably <2 mg / L; the leaching residue in the solid-liquid separation obtained in step (2) The ratio of the F residual amount to the F content in the rare earth concentrate is 5% or less, preferably 1% or less; the rare earth concentration of the rare earth chloride solution obtained after the aging and filtering is 150-250 g / L (REO), and the rare earth is leached The rate is 70% -95%, of which the leaching rate of Ce is 60% -95%. The following Table 1 shows the comparison between this method and the traditional fluorocarbon cerite treatment method to obtain hydrochloric acid leaching solution. It can be seen that the leaching solution concentration, total rare earth leaching rate, and Ce leaching rate obtained by this method are higher than those of the traditional fluorocarbon cerite method. The H ⁺ concentration is relatively low, and the F in the leachate is basically free, which has obvious technical advantages.

Table 1 Comparison of the hydrochloric acid leaching solution obtained by this method and the traditional treatment method of bastnasite

The smelting separator for the combined method for processing rare earth concentrates further includes spraying the fluorine-containing tail gas generated in the step (1) with water or an alkaline liquid, or the rare earth oxides and rare earth hydrated oxides. Defluorination of one or two adsorbents to recover rare earth fluoride products; and / or, a step of desulfurizing and recovering the sulfur-containing tail gas generated in step (3) to obtain a sulfuric acid product;

After the sulfur-containing tail gas generated in the sulfuric acid roasting process is subjected to desulfurization and recovery treatment, not only the tail gas emission reaches the standard, but also high-purity sulfuric acid products can be recovered and the concentration can reach more than 80%, which effectively solves the problem that the tail gas components in the traditional process contain F and equipment corrosion Severe attrition, difficult separation of F and S-containing substances, difficulty in meeting standards, and high operating costs.

The smelting separation process for treating rare earth concentrates by the combined method of the present invention adopts the method of atmosphere roasting-hydrochloric acid leaching-sulfuric acid roasting to treat rare earth concentrates containing fluorocarbon ceria, and controls the use of low-concentration hydrochloric acid in the hydrochloric acid leaching process. A stepwise acid leaching method resulted in a higher rare earth chloride solution (150-250g / L REO). At the same time, the use of the [CeF _x ] ^4-x coordination compound to make more Ce enter the solution So that the leaching rate of Ce can reach 60% -95%, and the total rare-earth leaching rate can reach 70% -95%; further, the process of the present invention utilizes the relationship between the Cl ^- reducibility and the solubility product and temperature of fluorinated rare earths, and aging through high temperature. It further reduced the F ^- content of the leachate. Compared with the traditional oxidative roasting-hydrochloric acid leaching process for the treatment of bastnasite, both the concentration of the leaching solution and the leaching rate of the rare earth are greatly improved, eliminating the step that the traditional process requires further evaporation and concentration to obtain a high concentration rare earth chloride solution, and the F in the solution The content is very low, which prevents F from entering the extraction system to generate three phases, and can directly enter the P507-HCl system to separate and purify a single rare earth element.

According to the smelting and separation process for treating rare earth concentrates by the combined method of the present invention, after the rare earth concentrates are roasted in atmosphere-hydrochloric acid leaching-aging at high temperature, only 5% -30% of the rare earths remain in the hydrochloric acid leaching slag, compared with The traditional process for processing mixed rare-earth concentrates has greatly reduced the consumption of concentrated sulfuric acid, and also greatly reduced the consumption of water in the water leaching process. 70% -95% of the rare earths are directly sent to the chlorination system to extract and separate the rare earths. It also drastically reduces the acid-base consumption of sulfuric acid leaching solution extraction and transformation into a rare earth chloride solution.

In the smelting and separation process for treating rare earth concentrates by the combined method of the present invention, the direction of fluorine is effectively controlled. First, during atmospheric roasting, most of the fluorine is converted into hydrogen fluoride gas into the tail gas, and the fluorine-containing product is prepared through adsorption and recovery treatment. Second, during the hydrochloric acid leaching process, a small amount of fluorine is leached into the rare earth chloride solution, and the fluorinated rare earth product is obtained by aging, so that the F ^- concentration in the rare earth chloride solution is <8mg / L, and the fluorine is prevented from entering the leaching residue. It solves the problem that it is difficult to treat the fluorine-containing and sulfur-containing mixed tail gas in the sulfuric acid roasting process. As the amount of rare earth remaining in the hydrochloric acid leaching residue is greatly reduced, the amount of concentrated sulfuric acid used in the sulfuric acid roasting process is also reduced, and the SO ₂ flue gas generated during the sulfuric acid roasting process is also reduced by more than 60%, which greatly reduces the waste gas and wastewater treatment costs. It is closer to the goal of cleaner production, eco-friendly, and has significant economic and environmental advantages as a whole. The effective recovery and treatment of F also solves the problem of the large amount of wastewater containing F in traditional processes, which is difficult to meet the standards. The industrial adaptability of the entire process is more extensive. It can comprehensively process a variety of complex minerals, and realize the environmental protection, efficient and clean production of mineral-type rare earth concentrates such as Baotou mixed rare earth concentrates, fluorocarbon cerium concentrates, and significant economic and social benefits. .

BRIEF DESCRIPTION OF THE DRAWINGS

In order to make the content of the present invention easier to understand clearly, the following further describes the present invention in detail based on the specific embodiments of the present invention and the accompanying drawings. Among them,

FIG. 1 is a flow chart of a smelting separation process for treating rare earth concentrates by a combined method according to the present invention.

detailed description

Example 1

The rare earth concentrate processed by the process described in this embodiment is a mixed rare earth ore of fluorocarbon cerium ore and monazite. According to the process flow chart shown in FIG. 1, the smelting separation of the rare earth concentrate is processed by the combined method described in this embodiment. The process includes the following steps:

(1) Roasting a mixed rare earth concentrate of fluorocarbon cerium ore and monazite in an air atmosphere (oxygen content 21%) at 500 ° C for 4 hours to obtain a roasted ore;

In this step, the HF that escapes during the roasting process is treated with water spray.

(2) The obtained roasted ore is added with hydrochloric acid at 25 ° C. for continuous continuous leaching in 4 stages. The initial concentration of hydrochloric acid is 6 mol / L, and the ratio of the amount of hydrochloric acid to the roasted concentrate is 1.0 mol hydrochloric acid / 100 g of rare earth concentrate. After solid-liquid separation, the rare-earth leaching solution and the leaching slag were collected, and the obtained rare-earth leaching solution had a rare-earth content of 238 g / L, a rare-earth leaching rate of 77%, and a Ce leaching rate of 70%;

In this step, the hydrochloric acid leaching step is preferably two or more steps of hydrochloric acid countercurrent leaching. After the first step of hydrochloric acid leaching, solid-liquid separation is used to obtain one step of rare earth leaching solution and one step of leaching slag. The rare-earth leaching solution of this step and the leaching slag of this step are obtained by solid-liquid separation. Among them, the rare-earth leaching solution of this step is returned to be used as the bottom water of the hydrochloric acid leaching in the previous step.

In this step, the method of adding hydrochloric acid for the leaching process is to perform continuous parallel leaching in 4 stages during the leaching process, and to control the concentration of hydrochloric acid, and add 1.5 mol / L, 2 mol / L, and 6 mol / L in the first to fourth stages, respectively. L, 8mol / L hydrochloric acid, the acidity of the mixed solution decreases between 0.1-0.05mol / L gradient;

In this step, the rare earth leaching solution is aged at 65 ° C for 4 hours, and the solid-liquid separation obtains a rare earth chloride solution and a rare earth fluoride precipitate. The F content in the rare earth chloride solution is 1.9 mg / L. Chemical rare earth products.

(3) After the obtained leaching slag is washed and dried to a moisture content of 9%, concentrated sulfuric acid is added and roasted at 300 ° C for 3 hours, and the mass ratio (w / w) of the concentrated sulphuric acid to the leaching slag is 0.3: 1. ;

The roasted product was collected and added with water at 25 ° C. for 4 h, and after neutralization and impurity removal, a 32 g / L rare-earth sulfate solution was prepared; the total rare-earth yield was 97%. The obtained rare-earth sulfate solution is subjected to extraction transformation to obtain a rare-earth chloride solution, which is combined with the rare-earth chloride solution in step (2) and subjected to extraction and separation to obtain a single rare-earth compound product.

In this step, the sulfur-containing waste gas generated during the sulfuric acid roasting process is recovered by spraying and absorbing the sulfuric acid product.

Example 2

The rare earth concentrate processed by the process described in this embodiment is a mixed rare earth ore of fluorocarbon cerium ore and monazite. The smelting and separation process of the rare earth concentrate processed by the combined method described in this embodiment includes the following steps:

(1) The mixed rare earth ore of fluorocarbon cerium ore and monazite is roasted at 500 ° C for 4 hours under a weakly oxidizing atmosphere in the air (by adjusting the opening of the intake valve to control the oxygen content to 12%). The opening degree of the valve is 50%, and the roasted ore is obtained;

In this step, the HF escaped during the roasting process is recovered by water spraying.

(2) The obtained roasted ore is added with hydrochloric acid at 25 ° C. for continuous continuous leaching in 4 stages. The initial concentration of hydrochloric acid is 6 mol / L, and the ratio of the amount of hydrochloric acid to the roasted concentrate is 1.0 mol hydrochloric acid / 100 g of rare earth concentrate. After solid-liquid separation, the rare earth leaching solution and the leaching slag were collected, and the rare earth content of the obtained rare earth leaching solution was 250 g / L, the rare earth leaching rate was 80%, and the Ce leaching rate was 75%;

In this step, the rare-earth leaching solution is aged at 80 ° C for 4 hours. The solid-liquid separation results in a rare-earth chloride solution and a rare-earth fluoride precipitate. The F content in the rare-earth chloride solution is 1.2 mg / L. Chemical rare earth products.

Example 3

(1) Roasting a mixed rare earth ore of fluorocarbon cerium ore and monazite under a water vapor atmosphere at 650 ° C for 4 hours, and the opening degree of the intake valve is 100% to obtain a roasted ore;

In this step, the HF escaped during the roasting process is recovered by using a rare earth oxide adsorbent to obtain a fluorinated rare earth product.

(2) The obtained roasted ore is added with hydrochloric acid at 25 ° C for continuous continuous leaching in 4 stages. The initial concentration of hydrochloric acid is 6 mol / L, and the ratio of the amount of hydrochloric acid to the roasted concentrate is 1.0 mol hydrochloric acid / 100 g of rare earth concentrate. After solid-liquid separation, the rare-earth leaching solution and the leaching slag were collected, and the obtained rare-earth leaching solution had a rare-earth content of 235 g / L, a rare-earth leaching rate of 75%, and a Ce leaching rate of 69%;

In this step, the hydrochloric acid leaching step is preferably two or more steps of hydrochloric acid countercurrent leaching. After the first step of hydrochloric acid leaching, solid-liquid separation is used to obtain one step of rare earth leaching solution and one step of leaching slag. The rare-earth leaching solution of this step and the leaching slag of this step are obtained by solid-liquid separation, wherein the rare-earth leaching solution of this step is returned to be used as the bottom water of the previous step of hydrochloric acid leaching, and the leaching slag of this step can be subjected to the next step of hydrochloric acid leaching.

In this step, the rare earth leaching solution is aged at 80 ° C for 4 hours. The solid-liquid separation results in a rare earth chloride solution and a rare earth fluoride precipitate. The F content in the rare earth chloride solution is 1.5 mg / L. Chemical rare earth products.

The roasted products were collected and added with water at 25 ° C. for 4 h. After neutralization and impurity removal, a 32 g / L rare-earth sulfate solution was prepared, and the total yield of the rare-earth was 95%. The obtained rare-earth sulfate solution is subjected to extraction transformation to obtain a rare-earth chloride solution, which is combined with the rare-earth chloride solution in step (2) and subjected to extraction and separation to obtain a single rare-earth compound product.

The steps of Example 4-23 are as in Example 1-3. The conditions of each step are shown in Table 2-4 below. The final total yield of rare earth is shown in Table 4:

Table 2

table 3

Table 4

It can be seen that a variety of complex rare earth minerals can be comprehensively processed by the present invention, and the industrial applicability of the entire process is wide. Most of the fluorine is converted into hydrogen fluoride gas into the tail gas by roasting in the atmosphere, and the fluorine-containing product is prepared through adsorption and recovery treatment; through the continuous leaching of multi-stage hydrochloric acid and the adjustment of the acidity, a highly concentrated rare earth chloride solution (150-250g / L REO) is obtained At the same time, the rare-earth leaching rate is guaranteed to reach more than 70%; the F ^- content of the leaching solution is reduced by aging, and a rare earth fluoride product is obtained to prevent fluorine from entering the leaching slag, which solves the problem that the fluorine-containing and sulfur-containing mixed tail gas in the sulfuric acid roasting process is difficult to treat Difficulties; the slag is further recovered by sulfuric acid roasting-water leaching, and the total yield of the rare earth is more than 95%. Green environmental protection, efficient and clean production of mineral-type rare earth concentrates have been achieved.

Obviously, the foregoing embodiment is merely an example for clear description, and is not a limitation on the implementation. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. There is no need and cannot be exhaustive for all implementations. However, the obvious changes or variations introduced thereby are still within the protection scope created by the present invention.

Claims

A smelting separation process for processing rare earth concentrates by a combined method, which is characterized by including the following steps:

(1) roasting and decomposing the rare earth concentrate in a certain roasting atmosphere to obtain a roasted ore;

(2) adding the obtained roasting ore to leaching rare earth with hydrochloric acid, and separating the rare earth leaching solution and leaching slag by solid-liquid separation;

(3) After the obtained leaching slag is subjected to dehydration treatment, concentrated sulfuric acid is added for roasting, and the roasted product is collected and subjected to water leaching, neutralization, and impurity removal to obtain a rare-earth sulfate solution.
The smelting separation process for treating rare earth concentrates in a combined method according to claim 1, wherein in the step (1), the roasting atmosphere in the roasting step includes one of water vapor, air, CO, and CO 2 Or more.
The smelting separation process for treating rare earth concentrates by the combined method according to any one of claims 1-2, wherein in the step (1), the roasting temperature in the roasting step is 350-650 ° C.
The smelting separation process for treating rare earth concentrates by a combined method according to any one of claims 1-3, wherein in the step (2), the hydrochloric acid leaching step is preferably two or more steps of hydrochloric acid countercurrent leaching After the first step of hydrochloric acid leaching, one step of rare earth leaching solution and one step of leaching slag are obtained by solid-liquid separation, and the one step of leaching slag is followed by the next step of hydrochloric acid leaching. Return to the bottom water used for hydrochloric acid leaching in the previous step. The leaching residue in this step can be used for the next step of hydrochloric acid leaching.
The smelting and separating process for treating rare earth concentrates by the combined method according to any one of claims 1-3, characterized in that in the step (2), the adding method of the hydrochloric acid is 2-5 in the leaching process Stage continuous co-current leaching, and hydrochloric acid is added in a concentration gradient during each stage of leaching to maintain the acidity of the mixed solution at 0.01-0.6 mol / L during the leaching process.
The method for smelting and separating rare earth concentrates according to any one of claims 1 to 5, wherein in the step (2), the leaching temperature of the hydrochloric acid leaching step is controlled to 10-75 ° C.
The smelting separation process for treating rare earth concentrates by a combined method according to any one of claims 1-6, wherein in the step (3), the mass ratio of the concentrated sulfuric acid to the dehydrated leaching slag (w / w) is 0.3-1.2: 1.
The smelting separation process for treating rare earth concentrates by a combined method according to any one of claims 1-7, wherein in the step (3), the temperature of the sulfuric acid roasting step is 200-450 ° C, and The temperature of the water immersion step is 20-50 ° C.
The smelting and separation process for treating rare earth concentrates by the combined method according to any one of claims 1 to 8, characterized in that in the step (3), further comprising extracting and separating the obtained rare earth sulfate solution, or extracting transformation or In the precipitation transformation step, a rare earth chloride solution is obtained, which is separated by extraction to obtain a single rare earth compound.
The smelting and separating process for treating rare earth concentrates by a combined method according to claim 1-9, characterized in that in the step (2), the obtained rare earth leaching solution is aged at 60-90 ° C for 1-5 hours, The solid-liquid separation yields a rare earth chloride solution and a fluorinated rare earth powder product; the obtained rare earth chloride solution is combined with the rare earth chloride solution obtained by converting the rare earth sulfate solution described in step (3), and a single rare earth is obtained by extraction and separation Compound.
The smelting and separation process for treating rare earth concentrates by the combined method according to any one of claims 1-10, characterized in that the fluorine-containing tail gas generated in the roasting process in step (1) is sprayed with water or an alkaline liquid Treatment, or defluorination of one or two adsorbents of rare earth oxides and rare earth hydrated oxides to recover rare earth fluoride products; and the sulfur-containing tail gas generated in the step (3) sulfuric acid roasting process is subjected to desulfurization recovery treatment, A sulfuric acid product was obtained.